Combine all the vegetables in a large bowl. In another bowl, combine the dressing ingredients and whisk together. Pour over the vegetables and toss very well. I like to use a container with a sealing lid and toss, then close and shake. I find it helps to combine the dressing so that you don’t have a pool of liquid at the bottom, but all the veggies have dressing.
My red onion was very strong, so I only used half. If you have a milder onion you might want to add more. This was so fresh and crisp and really good. Next time I might break down and buy a mandoline to get the veggies really sliced thin.